Casey Kasem's Little-Known Dementia is Heartbreaking, Docs Say

The mystery surrounding ailing disc jockey Casey Kasem deepened this week after his children told a Los Angeles judge that the radio legend suffers from Lewy body dementia, a disease that experts say is both common and widely underdiagnosed.

The 82-year-old Top 40 radio host remained missing Tuesday after his family said he was abruptly removed from a medical center that had been treating him for the disorder that resembles better-known dementias associated with Alzhemier’s and Parkinson’s diseases.

That concerns experts who help treat the estimated 1.3 million Americans and their families affected by Lewy body dementia, or LBD. It can be traumatic and disorienting for dementia patients, including those with LBD, to have their surroundings change suddenly, said Keith Fargo, director of scientific programs and outreach for the Alzhemier’s Association.

“In general, large changes are challenging to people with dementia,” Fargo said.

Lewy body dementia is often misdiagnosed as Alzheimer’s disease, but the two conditions have different causes and symptoms, said Dr. James E. Galvin, a professor of neurology at NYU Langone Medical Center. Alzheimer’s is characterized by abnormal brain plaques and tangles caused by the proteins known as beta amyloid and tau. LBD, however, is characterized by "Lewy bodies" — abnormal clumps of a protein called alpha-synuclein.

In Alzheimer’s patients, lapses in short-term memory are among the first symptoms, while LBD patients might encounter severe disruptions in attention and judgment, Fargo said.

Hallucinations, delusions and severe disruptions in sleep are also common in LBD, but not Alzheimer's, Galvin said. In addition, LBD patients might be severely sensitive to certain psychiatric and other medications and can suffer fatal reactions if they're given the drugs.

LBD is named for Friederich H. Lewy, who was researching Parkinson’s disease in the early 1900s when he discovered the abnormal protein deposits that disrupt brain function, according to the Lewy Body Dementia Association. It’s an umbrella term for two related diagnosis, dementia with Lewy bodies and Parkinson’s disease dementia.

It's tragic when anyone develops a terrible, fatal disease, Galvin said. But attention drawn by personalities like Kasem can lead to better understanding and more resources.

Los Angeles Superior Court Judge Daniel S. Murphy ordered a court investigator to find Kasem after hearing conflicting information about whether he was moved to a Native American reservation in Washington state or was removed from the country, a court spokeswoman told NBC News.

Kasem’s daughter, Kerri Kasem, was appointed her father’s temporary caretaker. She said she’d seen her father at an unidentified medical center last week and had a warm visit, but that his wife, Jean, removed the radio icon abruptly after that — and kept his location secret.

“So that’s why we are doing this — to find my father,” she told NBC News.